Dual purpose character generator

ABSTRACT

A dual purpose graphic form or character generator which can be used as a visual display or as a line printer when combined with any suitable image transfer process. Lines of print characters or other graphic signs or symbols are formed through an endless band by means of a plurality of light sources which are activated selectively with precise timing by means of an electronic selector circuit. The selector circuit determines the position of the characters with respect to the light sources and fires the light sources according to the information fed into it by a data source.

nited States Patent 1 [111 3,735,

Aydin et al. 1 May 22, 1973 [54] DUAL PURPOSE CHARACTER 3,458,655 7/1969 Thourson ..178/15 GENERATOR Prima Examiner-Kathleen H. Clafi [75] Inventors: Kemal M. Aydtn; Lester L. Selmck, Assistgu Examiner Kenneth Richardzon both of Stamford Attorney-S. A. Giarratana, Thomas W. Kennedy and [73] Assignee: The Singer Company, Little Falls, Charles Lepchinsky [5 7] ABSTRACT A dual purpose graphic form or character generator which can be used as a visual display or as a line printer when combined with any suitable image [22] Filed: Nov. 26, 1971 [21] Appl. No.: 202,477

521 U.S.Cl ..17s/15 transfer P Lines of P Characters or other 51 1m. (:1. .1104! 15/34 graph signs symbls are formed thmugh [58] Field of Search 178/15 95/4 endless band by means of a plurality of light sources n 3 l which are activated selectively with precise timing by means of an electronic selector circuit. The selector circuit determines the position of the characters with [56] References cued respect to the light sources and fires the light sources n- STATES PATENTS according to the information fed into it by a data source. 3,064,545 8/1960 Scantlin ..l78/l5 3,651,258 2/1972 Ammann ..l78/l5 11 Claims, 13 Drawing Figures SELECTOR CIRCUIT 1 DATA 20 SOURCE PATENTED I41Y22|973 3. 735,042

SHEET 1 BF 5 SELECTOR CIRCUIT LE y FIGI DATA SOURCE INVENTORS C L Emu RMEY PATENTED M21915 $735,042

SHEET 2 OF 5 l8 {l0 LIGHT LSELECTOR CIRCUIT SOURCE MULTIPLEX SLOT INVENTORS KEMAL M. AYDIN LESTER L. SELNICK PATENrfumYzzlm SHEET [1F 5 l23456789l0ll|2 l23456789|0lll2 FIG. 8

SHIFT CYCLE INDEX PULSE MEMORY ADDRESS 1 2 3 4 5 SHIFT REGISTER SHIFTH C. COUNTER DECREMENT 2 FIG. 9

INVENTORS KEMAL M. AYDIN LESTER L.SELN|CK BY C (Li A oP-NEY FIG. IO

DUAL PURPOSE CHARACTER GENERATOR BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates to a character generator which can be used as a visual display or a line printer.

It is an object of the present invention to provide a character generator which projects a shadow image of characters, symbols or shapes on a film mask as a direct view or in the printing version, the formed image is projected onto a photo-receptive medium as a latent print.

A further object of the present invention is to provide a light source for the present invention of the proper intensity, configuration, shape, and light spectral range for both the display version and the printing version of the apparatus. In addition, the light source has certain requirements relating to speed, uniformity, and life expectancy which give outstanding results. Moreover, a wide variety of different light sources, such as flash tubes, neon lamps, solid state lamps, and incandescent bulbs can be used with the present apparatus.

Another object of the present invention is to provide a rotating film mask in the form of a durable endless belt through which the characters are projected.

An object of the present invention is to provide an electronic selector circuit which activates the proper light source timing that corresponds to the incoming information fed to the circuit.

Another object of the present invention is to provide a character generator in the form of a printer which utilizes an image transfer process. Thus, the projected characters on the mask produce a latent image on the photo-sensitive medium.

An object of the present invention is to provide a character generator for display purposes in which each rotation of the mask across the light sources corresponds to a refresh cycle of the line displayed.

A further object of the present invention is to provide a multiplexed character generator which is designed so that one light source can be used for a plurality of print or display positions on a time sharing basis. The endless belt used to carry the character set may be easily adapted for multiplex operation.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be more fully described with reference to the accompanying drawings wherein:

FIG. 1 is a perspective diagrammatic view of the character generator constructed in accordance with the teachings of the present invention in which a moving mask is used for display purposes.

FIG. 2 is a perspective diagrammatic view of the character generator constructed in accordance with the teachings of the present invention in which a photosensitive medium picks up the characters generated and transfers the print onto paper or other suitable materials thereby creating a line printer.

FIG. 3 is a diagrammatic view of one form of the light source and associated structure and circuitry.

FIG. 3a is a diagrammatic view of an alternative embodiment of the structural arrangement shown in FIG. 3.

FIG. 4 is a diagrammatic view of the selector circuit control for the firing of the proper light source for a character or symbol.

FIG. 5 is a schematic view of the electronic selector circuit of the present invention for illuminating a particular character or symbol.

FIG. 6 is a diagrammatic view of a particular function of the electronic selector circuit operation.

FIG. 6a is a diagrammatic view of a second position of a particular function of the electronic selector circuit operation.

FIG. 7 is a diagrammatic view of the multiplex character generator which utilizes an endless belt to carry the character set and shows a single source for multiple display or print positions.

FIG. 8 is a diagrammatic view showing the operation of the multiplex feature of the invention.

FIG. 9 is a diagrammatic view of the shift cycle for the multiplexing operation.

FIG. 10 is a diagrammatic view of the index markings for the mask, and

FIG. 1 l is a block diagram of the multiplex character generator constructed in accordance with the teachings of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Referring to the FIGS. 1 and 2 of the drawings, a plurality of light sources 10 are shown for each character position. An endless belt mask 12, which may be negative or positive i.e., the characters may be substantially opaque and the background substantially clear or the characters substantially clear and the background substantially opaque, is shown which passes about spaced rollers 14. The drive for rollers 14 may be of any wellknown type, such as a constant speed or stepping motor with a known drive transmission, for example, a belt, gears, etc. The position of the characters to be pro jected through the mask is set by index marks 16. The endless belt mask 12 moves across the bank of light sources 10 and an electronic selector circuit 18 which receives information fed into it by a data source 20 activates selectively the particular light source when the desired character is lined up with the particular position. In this regard, the index marks 16 are sensed by a photo-detector 22 and the signal sent to the timing circuit 54 of the electronic selector circuit 18. Thus, if it is desired to generate the letter A at position 1, the particular light source 10 is activated by theselector circuit when the letter A is opposite the particular light source and aligned therewith. The same results occur when the letter B is desired to be projected on the negative mask 12, etc. In this visual display version of the present invention, each rotation of the mask across the bank of light sources corresponds to a refresh cycle of the line displayed. The refresh cycle is such that there is a minimum of flicker of images. A phosphorescent screen can be used additionally which retains the images and further minimizes flicker.

As seen in FIG. 2, the printing version of the present invention is illustrated in which the character mask 12 is shown oriented in a different manner from that shown in FIG. 1 but being in close proximity to a rotatable photo-sensitive drum 24 similar to the type used in xerography. The projected characters on the mask 12 produce a latent image on the photo-sensitive drum 24. It should be noted that each rotation of the endless belt mask 12 corresponds to one printed line or more or patterns. The projected characters on the mask produce a latent image on the sensitive medium on the drum 24, and this latent image passes through a developing station 26 which in turn prints or transfers the characters on plain-paper 28, or other suitable material.

FIGS. 3 and 3a show two possible light source arrangements in which a shadow channel 30 is aligned with a flash tube or bulb 32. A selector circuit 34 is connected directly to the bulb 32 in FIG. 3, while in FIG. 3a, a light pipe 36, such as fiber optics, is utilized to transmit the flash from bulb 32 to the shadow channel 30 and hence to the moving mask 12. In addition, lenses or other optical means (not shown) can be used to enhance the quality of the projected images. The synchronization of the light pulses or flashed from bulb 32 is important with respect to adjacent dimensional tolerances from character to character so that there is no interference from one character to another during the projection of the line of characters on the mask 12.

The film mask 12 is preferably constituted of Mylar and therefore has high strangth characteristics. However, it is within the scope of the present invention to use other materials, for example, steel or rubber belts which are capable of carrying a strip of characters at very high speed applications. The belt can he stepped or moved continuously as required.

FIGS. 4 and 5 refer to the details of the electronic selector circuit 18 which selectively activates the proper light source to correspond to the incoming information supplied by the data source 20. As seen in FIG. 4, if the incoming information includes the letter B at the position 4, the selector circuit 18 decodes the information and senses when the letter B is in the 4th position and activates the light source at that precise time.

Referring to FIG. 5, the electronic selector circuit comprises a memory 38, a character position sensing device 22 and a comparator circuit 42 and additional components. The information or data source feeds information to the memory. The comparator circuit 42 has fed into it information from a character counter, and a memory 38. The output of comparator 42 is furthermore connected to a shift register 48. Connected to the latter is an interface circuit 50 which in turn is coupled to a plurality of drivers 52. A timing circuit 54 is shown connected to the meomory 38, character counter 44, position counter 46, and trigger circuit 56. It is to be understood that although this particular electronic selector circuit is used in the present system, other types of electronic selector circuits may be utilized which will also properly actuate the light sources as explained hereinabove.

As will be explained in detail hereinafter, a light source 10 can expose one or more print or display positions and although 80 print or display positions are contemplated in the instant construction, other numbers of print or display positions may be selected within the teaching of the present invention. However, for simplification of the disclosure, in some instances the generator has been reduced to four print or display positions and a character set of six characters (A, B, C, D, E, and F). The expansion of the number of positions changes only the number of components in the circuit.

Referring to FIG. 5, it will be noted that the data to be printed or displayed is stored in the memory 38 which may be a core or semi-conductor memory that holds a given amount of information. The coded information can be any commercial standard, and the number of characters stored in the memory is equal to the number of print positions, or multiples thereof. As stated hereinbefore, in the present preferred embodiment of the invention, there are print or display positions, and the memory stores 80 characters. The memory locations correspond to the print or display positions, that is, a characters stored in location 1 will print or display on positions 1, etc.

The operation of the present apparatus is as follows: Initially, the print or display information is transferred and stored in the memory 38 by the information source 20. After the information is stored, the index sensor 22 senses the leading edge of the index mark 16 on the character mask 12 and activates the timing circuit 54. When the timing circuit becomes operative, it accomplishes the following operations in sequence: l) Increment the position counter 46 which at first becomes the code for the first character, as seen in FIG. 4, the code for the character A. (2) Preset the character counter 44 to the code established in the position counter 46. (3) Retrieve the character at the location 1 of the memory 38 and compare the code with the character counter 44. If both are the same, the output of the comparator circuit 42 becomes a logic 1. (4) Shift the shift register 48 one position. It the input to the shift register is a logic 1 from the comparator circuit 42, then the logic 1 is shifted to position 4 of the shift register 48. (5) Decrement the character counter 44. (6) Repeat the steps 3-5 in accordance with the number of positions of print or display. (7) Activate the trigger circuit 56. The above cycle is repeated depending upon the number of characters. In the present example, the characters are repeated six times.

With reference to the trigger circuit 56, it should be noted that the circuit triggers all the lamps 10 simultaneously, and if a particular lamp is gated through the driver circuit according to the output of the shift register position, it flashes and exposes the character opposite to it or aligned therewith. That is, when positions 1, 2, 3, and 4 of the shift register 48 are logic 1, the lamps in these positions are flashed. Thus, the shift register 48 holds the lamp firing information for a particular position of the mask 12 with respect to the print or display positions, i.e., in the first condition the letter A is opposite print or display position 1; in the second condition, the letter A is opposite position 2 and B is across from print or display position 1, as seen in FIG. 6. In the first condition, if the letter A is desired in position 1, the shift register position 1 output is set to logic 1 and in the second condition, if the letter B is desired in position 1, the shift register position 1 is set to logic 1. If the letter A is desired in position 2, then the shift register 2 position is set to logic 1. In this manner, any character or symbol of the character or symbol set can be made to form an image at any print or display position.

As is seen in FIG. 7, the present character generator can be multiplexed. Thus, one light source can be utilized for a number of print or display positions on a time sharing basis. In this regard, the endless belt 12 can be elongated for multiplex operation. In this connection, the present arrangement is considered superior to the use of a disc or a drum for light projection which obviously have practical size limitations. The principle of light source sharing is illustrated in FIG. 7 in which the character or symbol set moves across the multiplex slot 58 which has the desired number of print or display positions, for example, 4. The selector circuit 18 determines the position of the characters inside a slot relative to the print or display positions. It then compares this information with the information from the source 20, and if they match, it activates the light source and thereby projects the characters. The pitch I, as seen in FIG. 7, is equal to the product of a single position width a and the number of print or display position in a given slot. In the example shown in FIGS. 7, P= 4a.

The basic electronic selector circuit 18, as seen in FIG. 8, is similar to the device previously described without the multiplex feature. However, the present an rangement has the additional structure for shifting the lamp fire information with respect to the character position inside a multiplex slot 58. Thus, the relative relationship between the characters and print positions inside the slots is shown in FIG. 8. In this connection, when the letter A is aligned with position 9, the letter B is aligned with position 5, and letter C is aligned with position 1. Moreover, when the letter A is aligned with position 10, then the letter B is aligned with position 6, and the letter C is aligned with position 2. The display or print positions are integerly related to the locations in the memory. In the first case, the locations are 1, 5, 9, 13, etc; and in the second case, the locations are 2, 6, 10, 14, etc. Accordingly, the difference between Iocations is equal to the number of positions in the slot 58. The shifting is accomplished during the time when the characters move from one position to another. In the case of multiplexing, the shift register has the same number or registers as there are multiplex slots, in this case 20. During a shift cycle for a print position, shifting is done at multiple intervals of the memory print 10- cations. The interval is equal to the number of print positions in a slot which in the present case is 4. As seen in FIG. 8, when the letter C is across position 1, the letter B across position 5, and the letter A across position 9, shifts occur in the shift register 58 when the locations 1, 5, and 9 are compared to the character counter 44. The timing diagram as shown in FIG. 9, shows the shift cycle for positions 2, 6, 10, etc. This is the shift cycle before the letter A comes to position 2. In this regard, a shift is made every four memory access starting at the 2 count. The start selection for the shift register shift is accomplished by adding a multiplex counter. This counter counts the index marks and resets to zero at the end of each multiple of the multiplex number (the number of positions inside the multiplex slot), and it feeds this information into the timing circuit 54 which in turn generates the shift signals in the shift register 48.

The number of index marks 16 between characters is equal to the number of positions in a multiplex slot 58. In the present illustration the number is 4. The character relationship to the index numbers is shown in FIG. 10. Referring now to FIG. 9 in which the position counter 46 is illustrated showing increments at every multiplex multiple of the index marks 16 (FIG. 10). This is done by incrementing the position counter 46 at every reset of the multiplex counter. The character counter 44 is decremented following each shift. With the exception of the shift resiter 48, the shift control, position counter increment difference, and the character counter decrement difference, the multiplexed version of the electronic selector circuit is similar to the structural arrangement illustrated in FIGS. 1 and 5.

FIG. 1 l is a block diagram of the multiplex character generator showing the multiplex slot 58 together with the multiplex counter 60. Otherwise, the same reference numerals as applied in FIG. 5 for like structures appear in FIG. 11.

However, it should be noted that the light sources 10, seen in FIGS. 1, 2, 3, 3a, 4, 6, and 6a, are all provided with shadow channels or light baffles 30.

What is claimed is:

l. A dual purpose character generator for generating a line of characters comprising:

a. An elongated belt mask containing thereon, along a line on said mask, a plurality of characters equally spaced by an amount at least equal to the character spacing on the line to be generated said mask further containing thereon an index mark for each character position;

b. a plurality of light sources equal to the total number of character positions on the line to be generated located on one side of the belt and having their beam axes aligned with the line of characters on said mask;

c. means for moving said mask across the beam axes of said light sources;

(1. a data source storing a representation of the characters to be generated at each position on the line;

e. means for sensing the index marks on said mask thereby providing an indication of the relative positioning of characters on said mask with respect to said light sources;

f. an electronic selector circuit having as inputs information from said data source and the output of said sensing means and providing outputs to activate ones of said plurality of light sources when the selected character for a character position is aligned with the light source for that character position whereby each time said plurality of characters is moved past said plurality of light sources a complete line will be generated.

2. A dual purpose character generator as claimed in claim 1 further comprising a photo-sensitive device adjacent to said mask for receiving a latent image of the projected line of characters, and means for printing said characters on paper or other suitable material.

3. A dual purpose character generator as claimed in claim 2 wherein said photo-sensitive device is a drum.

4. A dual purpose character generator as claimed in claim 1 wherein said light sources are-flash bulbs.

5. A dual purpose character generator as claimed in claim 4 further comprising a shadow channel, a light pipe for transmitting the flash of said flash bulb to said shadow channel and hence to said moving mask.

6. A dual purpose character generator as claimed in claim 1 wherein said electronic selector circuit comprises:

a. a memory obtaining inputs from said data source said memory storing a representation of the character to be generated at each of said character positions;

b. means obtaining an input from said sensing means to provide an indication of the current character being sensed;

c. a character counter having an input from said current character means, said input presetting the output of said counter upon indication of a character being sensed;

d. a comparator having an input from said memory and from said character counter means and providing an output when said two character correspond;

e. a shift register obtaining its data input from said comparator;

f. timing means to sequentially provide the successive character representations form said memory to said comparator, said timing means further decrementing said character counter each time a new character is supplied and thereafter providing a shift command to said shift register;

g. a plurality of drivers, one being provided for each of said light sources;

h. an equal plurality of interface circuits coupling the outputs of respective positions in said shift register as enabling inputs to said drivers;

i. a trigger circuit responsive to an output from said timing circuit indicative of the completion of a line of character having been sequenced to said comparators providing a trigger inputs to all of said light sources thereby triggering those light sources which have been enabled by said shift register whereby, for each character sensed by said sensing means, a comparison will be made for each character position and all characters corresponding to a character desired in that position will be generated at one time with a total line of characters being generated after all characters have moved past said sensing means.

7. The invention according to claim 1 wherein the characters on said mask are spaced an integral number of character spaces greater than one apart from each other and said plurality of light sources are similarly spaced whereby each light source may generate characters for a number of character positions equal to said integral number.

8. The invention according to claim 7 wherein said electronic selector circuit further includes means to differentiate between the multiple character positions which may be generated by a single light source.

9. A dual purpose character generator as claimed in claim 1 wherein said elongated belt is endless.

10. A dual purpose character generator as claimed in claim 1 wherein said sensing means comprise a light source on one side of said belt to intersect said index marks and a photodetector on the other side of said belt aligned to intersect the beam from said light source.

11. A dual purpose character generator as claimed in claim 1 wherein said mask is a negative mask. 

1. A dual purpose character generator for generating a line of characters comprising: a. An elongated belt mask containing thereon, along a line on said mask, a plurality of characters equally spaced by an amount at least equal to the character spacing on the line to be generated said mask further containing thereon an index mark for each character position; b. a plurality of light sources equal to the total number of character positions on the line to be generated located on one side of the belt and having their beam axes aligned with the line of characters on said mask; c. means for moving said mask across the beam axes of said light sources; d. a data source storing a representation of the characters to be generated at each position on the line; e. means for sensing the index marks on said mask thereby providing an indication of the relative positioning of characters on said mask with respect to said light sources; f. an electronic selector circuit having as inputs information from said data source and the output of said sensing means and providing outputs to activate ones of said plurality of light sources when the selected character for a character position is aligned with the light source for that character position whereby each time said plurality of characters is moved past said plurality of light sources a complete line will be generated.
 2. A dual purpose character generator as claimed in claim 1 further comprising a photo-sensitive device adjacent to said mask for receiving a latent image of the projected line of characters, and means for printing said characters on paper or other suitable material.
 3. A dual purpose character generator as claimed in claim 2 wherein said photo-sensitive device is a drum.
 4. A dual purpose character generator as claimed in claim 1 wherein said light sources are flash bulbs.
 5. A dual purpose character generator as claimed in claim 4 further comprising a shadow channel, a light pipe for transmitting the flash of said flash bulb to said shadow channel and hence to said moving mask.
 6. A dual purpose character generator as claimed in claim 1 wherein said electronic selector circuit comprises: a. a memory obtaining inputs from said data source said memory storing a representation of the character to be generated at each of said character positions; b. means obtaining an input from said sensing means to provide an indication of the current character being sensed; c. a character counter having an input from said current character means, said input presetting the output of said counter upon indication of a character being sensed; d. a comparator having an input from said memory and from said character counter means and providing an output when said two character correspond; e. a shift register obtaining its data input from said comparator; f. timing means to sequentially provide the successive character representations form said memory to said comparator, said timing means further decrementing said character counter each time a new character is supplied and thereafter providing a shift command to said shift register; g. a plurality of drivers, one being provided for each of said light sources; h. an equal plurality of interface circuits coupling the outputs of respective positions in said shift register as enabling inputs to said drivers; i. a trigger circuit responsive to an output from said timing circuit indicative of the completion of a line of character having been sequenced to said comparators providing a trigger inputs to all of said light sources thereby triggering those light sources which have been enabled by said shift register whereby, for each character sensed by said sensing means, a comparison will be made for each character position and all characters corresponding to a character desired in that position will be generated at one time with a total line of characters being generated after all characters have moved past said sensing means.
 7. The invention according to claim 1 wherein the characters on said mask are spaced an integral number of character spaces greater than one apart from each other and said plurality of light sources are similarly spaced whereby each light source may generate characters for a number of character positions equal to said integral number.
 8. The invention according to claim 7 wherein said electronic selector circuit further includes means to differentiate between the multiple character positions which may be generated by a single light source.
 9. A dual purpose character generator as claimed in claim 1 wherein said elongated belt is endless.
 10. A dual purpose character generator as claimed in claim 1 wherein said sensing means comprise a light source on one side of said belt to intersect said index marks and a photodetector on the other side of said belt aligned to intersect the beam from said light source.
 11. A dual purpoSe character generator as claimed in claim 1 wherein said mask is a negative mask. 